Just a quick note.

We use to remove material off the back of the cam lobe in our B&S go cart engine.
Dad was a Ford mechanic and he sanded the the non lobe side of the cam and re polished it with copus cloth.

He said there was very little pressure on that part of the cam and it would last as long as the engine would.

In retrospec it simply gave more lift and quicker cam timing.

You should be able to find out how much lift your engine could take before the valve spring bound up
and go from there.
Remember about the rocker arm ratio.